Before developing the tandem helicopters for which he is known, Frank Piasecki built and flew the PV-2 single-rotor craft in 1943. A result of three years' research by his company, the P-V Engineering Forum, it had a three-bladed, 25-foot (7.6-meter) rotor and was 22 feet (6.7 meters) long.

Credits - Hiller Aviation Museum